The global chemical weapons watchdog is inviting private companies to bid to get involved in destroying Syria's stockpile of toxic agents and precursor chemicals.

The Organization for the Prohibition of Chemical Weapons is posting a request for "expressions of interest" from companies who want a role in "the treatment and disposal of hazardous and non-hazardous organic and inorganic chemicals."

The agency, which won the Nobel Peace Prize this year, has been directed by the United Nations to oversee the destruction of the Syrian government's chemical weapons. The unprecedented disarmament in the midst of a civil war now in its third year was launched following an Aug. 21 chemical weapons attack on a Damascus suburb that killed hundreds of civilians.

The U.S. and Western allies accused the Syrian government of being responsible for that attack, while Damascus blames the rebels. Syria joined the OPCW and agreed to dismantle its chemical arsenal to ward off possible U.S. military strikes.

What needs to be destroyed involves a wide range of chemical agents. A senior OPCW official, speaking on condition of anonymity because he was not authorized to discuss the issue publicly, said Thursday that more than 700 tons of Syrian chemicals listed can be destroyed at regular commercial facilities.

The most toxic and weaponized chemicals in the Syrian stockpile will still have to be destroyed at a secure facility under OPCW supervision.

The OPCW is considering the option of destroying the most toxic parts of Syria's stockpile at sea on a mobile destruction facility on a large ship or barge. That option gained momentum after Albania last week refused a U.S. request to host the destruction of Syria's chemical arsenal, a serious blow to efforts to destroy that stockpile by mid-2014.

However, the OPCW official said most of Syria's stockpile involves precursor chemicals - which have to be mixed to turn them into weapons. He said the Albania setback should not deter other nations or companies from getting involved.

The OPCW official said "ready chemical warfare agents" only amount to about 20 tons of the approximately 1,300 tons of Syrian chemicals that have to be destroyed. None of it is the nerve agent sarin, he said, though Syria's stockpile does include chemicals that can be mixed to make sarin. He declined to detail what chemical weapons are in the arsenal, but reports previously have mentioned mustard gas.

Chemicals listed in the "expressions of interest" request "can easily be disposed of at any industrial chemical disposal facility," the official said.

Ralf Trapp, a French-based chemical weapons disarmament consultant and scientist, agreed, saying the list was made up of "chemicals that can be disposed of by normal industrial chemical waste treatment companies, and none pose a direct, immediate chemical weapons risk."

The British Foreign Office said it would study any British expressions of interest.

"We shall have to look at exactly what is being proposed," a Foreign Office spokesperson said on customary condition of anonymity. "There is no objection to them expressing interest and we would expect normal health and safety and environmental regulations to be observed."

The OPCW says it already has ended Syria's ability to create new chemical weapons by overseeing measures to decommission its facilities for mixing and loading chemicals into munitions like rockets. Syria also has "verifiably destroyed" 63 per cent of its unfilled chemical munitions. The OPCW official said Syria now says it has destroyed 100 percent of its munitions, although that number has yet to be verified by international inspectors.

"Because Syria's chemical weapons program has been dismantled the way it has, what you are left with is basically industrial chemicals and toxic chemicals," he said.

Under a destruction plan approved by the OPCW last week, Syria also will be required to destroy its stocks -- estimated at around 100 tons -- of a chemical called isopropanol, which can be used as an ingredient of sarin.

Even if companies now come forward to dispose of chemicals, a major challenge remains - getting them to a port and out of Syria amid a devastating civil war. The fighting in Syria has killed some 120,000 people, according to activists, and forced millions to flee the country.